Electrophysiological analysis of brainstem neurons subserving autonomic and motor oral functions

通过电生理学和行为学研究，研究了神经网络在脑干辅助自主神经和运动口腔功能中的作用。在电生理学研究中，采用全细胞膜片钳技术分析了脑干切片中上唾液神经元的生物物理特性。用细胞内记录技术在切片上分析三叉神经运动神经元的神经活动。支配舌的SS神经元表现出显著的瞬时外向电流(A-电流)，放电频率高达70赫兹。那些支配唾液腺的人表现出持续时间较长的A电流，并发出高达30赫兹的电流。分布于不同靶点的SS神经元散在分布于延髓外侧网状结构，有3~4个主树突伸向背腹约700μm。两种SS神经元呈现相似的全细胞电流，其中一些神经元可被印防己毒素、2-氨基-5-磷酸-戊酸(AP-5)和6-氰基-7-硝基-2，3-二酮(CNQX)拮抗，提示突触后电流的主要成分可能由GABAA-介导。NMDA型和非NMDA型受体。在行为学研究中，慢性记录自由活动大鼠颌下腺的唾液流量和咬肌的活动。在咀嚼过程中。唾液量和肌肉活动总是平行的。静脉注射阿朴吗啡引起呕吐时，唾液流量与胃的运动有关，但现在与颌骨的运动有关。通过这些研究，我们得出结论，中枢神经系统整合了自主神经和口腔运动功能，这两种功能的接触点可能位于脑干下部，特别是外侧网状结构。在一项新的研究项目中，应该分析三叉神经运动核前运动神经元的活动。

Neural network in the brainstem subserving autonomic and motor oral functions was investigated by electrophysiological and behavioral studies. In the electrophysiological study, biophysical properties of the superior salivatory (SS) neurons were analyzed by the whole-cell patch clamp technique in sliced brainstem preparations. Neural activity of the trigeminal motor neurons were also analyzed by the intra-cellular recording technique in sliced preparations. The SS neurons innervating the tongue displayed a prominent transient outward current (A-current), and fired up to 70 Hz. Those innervating the salivary glands expressed A-current lasting longer period, and fired up to 30 Hz. The SS neurons innervating the different targets scattered and intermingled in the lateral reticular formation of the medulla oblongata, which have 3-4 main dendrites that extended dorso-ventrally about 700 μm. The two kinds of SS neurons showed similar whole cell currents which of some neurons were antagonized by picrotoxin, 2-amino-5-phosphono-valeric acid (AP-5) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), suggesting that major components of the postsynaptic currents could be mediated by GABA_A-. NMDA- and non-NMDA-receptors. In behavioral study, salivary flow from the submandibular gland and activity of the masseter muscle were chronically recorded from the freely moving rats. During chewing. the amount of saliva and muscle activity were always parallel. When emesis was yielded by intravenous injection so apomorphine, salivary flow rate was correlated with movement of the stomach, but now with jaw movements.Through these studies, we conclude that the central nervous system integrates the autonomic and motor oral functions, and it is likely that a contact point between the two functions is situated in the lower brainstem especially the lateral reticular formation. The activity of the pre-motor neurons of the trigeminal motor nucleus should be analyzed in a new research project.